Restore SIGPIPE default action for subprocesses

Python ignores SIGPIPE on startup, because it prefers to check every
write and raise an IOError exception rather than taking the signal. Most
Unix subprocesses don't expect to work this way. This patch (adapted
from Colin Watson's post at http://tinyurl.com/2a7mzh5) sets SIGPIPE
back to the default action for quantum.agent.linux.utils.execute,
quantum.common.utils.execute and quantum-rootwrap created subprocesses.

Fixes bug 1053364

Change-Id: Ib805f1f8846c245b75a5ea64278c840b823c1fb2

diff --git a/bin/quantum-rootwrap b/bin/quantum-rootwrap
index bb7fbc0d5dd3201ccc32865bcf54dee45674a7ac..96939ae2ff2de4a7cf813e558e96b7443c0013e4 100755 (executable)
--- a/bin/quantum-rootwrap
+++ b/bin/quantum-rootwrap
@@ -38,6 +38,7 @@
 
 import ConfigParser
 import os
+import signal
 import subprocess
 import sys
 
@@ -47,6 +48,12 @@ RC_NOCOMMAND = 98
 RC_BADCONFIG = 97
 
 
+def _subprocess_setup():
+    # Python installs a SIGPIPE handler by default. This is usually not what
+    # non-Python subprocesses expect.
+    signal.signal(signal.SIGPIPE, signal.SIG_DFL)
+
+
 if __name__ == '__main__':
     # Split arguments, require at least a command
     execname = sys.argv.pop(0)
@@ -84,6 +91,7 @@ if __name__ == '__main__':
                                stdin=sys.stdin,
                                stdout=sys.stdout,
                                stderr=sys.stderr,
+                               preexec_fn=_subprocess_setup,
                                env=filtermatch.get_environment(userargs))
         obj.wait()
         sys.exit(obj.returncode)

diff --git a/quantum/agent/linux/utils.py b/quantum/agent/linux/utils.py
index 70f09414f0e1106faf979e7ca2778f59e28f455c..e8f3b716708ee86ad235f0d7bd2db9dc376ecf5f 100644 (file)
--- a/quantum/agent/linux/utils.py
+++ b/quantum/agent/linux/utils.py
@@ -21,6 +21,7 @@ import fcntl
 import logging
 import os
 import shlex
+import signal
 import socket
 import struct
 
@@ -30,6 +31,12 @@ from eventlet.green import subprocess
 LOG = logging.getLogger(__name__)
 
 
+def _subprocess_setup():
+    # Python installs a SIGPIPE handler by default. This is usually not what
+    # non-Python subprocesses expect.
+    signal.signal(signal.SIGPIPE, signal.SIG_DFL)
+
+
 def execute(cmd, root_helper=None, process_input=None, addl_env=None,
             check_exit_code=True, return_stderr=False):
     if root_helper:
@@ -42,6 +49,7 @@ def execute(cmd, root_helper=None, process_input=None, addl_env=None,
         env.update(addl_env)
     obj = subprocess.Popen(cmd, shell=False, stdin=subprocess.PIPE,
                            stdout=subprocess.PIPE, stderr=subprocess.PIPE,
+                           preexec_fn=_subprocess_setup,
                            env=env)
 
     _stdout, _stderr = (process_input and

diff --git a/quantum/common/utils.py b/quantum/common/utils.py
index 3d6db076a93979747a32c0da5a9992c5f781b008..d76c2ae093947c750e4b16a1dcb86e5e05cd06a7 100644 (file)
--- a/quantum/common/utils.py
+++ b/quantum/common/utils.py
@@ -23,6 +23,7 @@
 
 import logging
 import os
+import signal
 import subprocess
 import uuid
 
@@ -47,6 +48,12 @@ def boolize(subject):
     return subject
 
 
+def _subprocess_setup():
+    # Python installs a SIGPIPE handler by default. This is usually not what
+    # non-Python subprocesses expect.
+    signal.signal(signal.SIGPIPE, signal.SIG_DFL)
+
+
 def execute(cmd, process_input=None, addl_env=None, check_exit_code=True):
     logging.debug("Running cmd: %s", cmd)
     env = os.environ.copy()
@@ -54,6 +61,7 @@ def execute(cmd, process_input=None, addl_env=None, check_exit_code=True):
         env.update(addl_env)
     obj = subprocess.Popen(cmd, shell=True, stdin=subprocess.PIPE,
                            stdout=subprocess.PIPE, stderr=subprocess.PIPE,
+                           preexec_fn=_subprocess_setup,
                            env=env)
     result = None
     if process_input is not None: